Method and system for correctly identifying specific RFID tags

ABSTRACT

A system and method for identifying a specific RFID tag includes RFID reader circuitry, such as within an RFID reader, configured for sending and receiving RF signals to detect RFID tags and for obtaining signal parameter information associated with the RFID tags. Processing circuitry is configured for using the signal parameter information for one or more tags of the RFID tags and calculating a tag score for the one or more RFID tags. The processing circuitry is further configured for determining a specific RFID tag using the tag scores for the one or more RFID tags.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuing application that claims the benefit ofpriority to co-pending U.S. patent application Ser. No. 12/841,798,filed on Jul. 22, 2010, the entire contents of which is herebyincorporated by reference.

TECHNICAL FIELD

This invention relates generally to systems for reading radio frequencyidentification (RFID) tags, and more specifically, to a system that canidentify a specific RFID tag on a product in the vicinity of other RFIDtags.

BACKGROUND

Storage and management of inventory is a critical function of manybusinesses, including the manufacturing, retail, and shippingindustries. For efficiency purposes, it is desirable to communicateproduct information to a centralized inventory tracking system as theproduct is being removed or placed on shelves, rather than requiring aseparate entry of product information at a central location afterremoval or placement of the product.

One conventional method for communicating product information to aninventory tracking system includes UPC bar codes that are placed on theproducts and portable bar code scanners that are carried by the workersmanipulating the product. Portable bar code scanners are typicallyplugged in as an attachment to a portable electronic device such as amobile computer device. The scanners are used to scan the codes of UPClabels or information on a variety of different items for the purpose ofmanaging, storing, shipping, or otherwise handling such items. Suchscanners use optical light signals that are passed over the UPC does toread the codes. Generally, the scanners are pointed at the UPC codes.

While UPC codes and scanners to read such codes provide a convenientsystem for capturing inventory information, such a system has severaldrawbacks. First, UPC scanners require a line-of sight to the UPC labelor graphic on a package in order to read the code. This may be difficultto achieve when lining up the scanner with the UPC code. Additionally,UPC codes on products or packaging can be damaged or marked up so thatreading the code becomes nearly impossible. Consequently, the use ofradio frequency identification (RFID) tags has increased, and RFID tagsare increasingly growing in popularity to replace the conventional UPCbarcode tracking system.

When used on products as an inventory label, RFID tags can communicatedata to an RFID reader somewhat similar to a UPC code. An RFID tagincludes a microchip with data, an antenna, and sometimes a power sourcesuch as a battery (e.g. active RFID tag). An RFID reader also has anantenna, and the RFID reader's antenna transmits electromagnetic energyin the form of an RF beam or radio waves to the vicinity of the RFIDtags. Each RFID tag that is located within the range of the RFID readerthen energizes and sends identification information back to the RFIDreader via RF radio signals. RFID tags, because they radiate theirinformation as radio signals, may be read without having a line-of-sightarrangement between an RFID reader and a tag. While readers often focustheir RF beam for efficiency, the RFID read does not have to bespecifically pointed at a particular tag like a UPC reader does. In theinventory example, the identification information from an RFID tag mayinclude an Electronic Product Code (EPC), which is a direct replacementfor the UPC bar code. Thus, an RFID reader can scan and detect allproducts carrying an RFID tag within the range of the reader, and nomanual scanning of each product is necessary.

Such non-directivity to the RFID scan, however, presents another issue.One drawback of current RFID reader systems is that several RFID tagswill be read when they are within the range of the RFID reader. The RFIDread process is not selective when a worker removes a specific productfrom a shelf full of products carrying RFID tags, a reading on an RFIDreader will include the EPC or identification information of all thetagged products in the vicinity of the reader's RF beam, not just theselected product removed from the shelf. If the specific RFID tag on theremoved product cannot be determined, then the RFID reader will not beable to communicate meaningful information to a centralized inventorysystem. Alternatively, when a worker is moving around and scanninginventory in a particular area, multiple reads may occur on multipletags, even though information from only a specific tag is desired.Consequently, it is desirable to have a better control of the readingprocess and selectively in correctly identifying an RFID tag on aspecific product or item.

SUMMARY

The invention according to one embodiment includes a system foridentifying a specific RFID tag attached to an item. The system includesRFID reader circuitry configured for sending and receiving RF signals todetect RFID tags and for obtaining signal parameter informationassociated with the RFID tags. Signal parameter information is obtainedregarding the RF signals received by the antenna from one or more of theplurality of tags. The signal parameter information is used to calculatea tag score for the RFID tags and to determine a specific RFID tag usingthe tag scores for the tags.

In one embodiment, the reader circuitry or RFID reader is operable fordetermining a received signal strength indication (RSSI) value and anoccurrence frequency value for each of the RFID tags. Using receivedsignal strength indication and occurrence frequency values, tag scoresare calculated for the RFID tags with processing circuitry running analgorithm. The processing circuitry can be in a separate device or withthe reader circuitry. A difference between the highest tag score of theRFID tags and the next highest tag score is compared a first thresholdvalue to determine a specific RFID tag using the tag scores. The RFIDtag associated with the highest tag score is selected as the specificRFID tag if the difference exceeds the first threshold value.

The RSSI and occurrence frequency values are added and averaged for themeasured RFID tags to calculate a tag score for each RFID tag. Also,before being added and averaged, the RSSI values and occurrencefrequency values might be normalized in the process, such as by dividingthe RSSI value by the maximum detected RSSI value, and by dividing eachoccurrence frequency value by the maximum occurrence frequency valuedetected. One or more of the RSSI value and occurrence frequency valuesmight also be emphasized by multiplying the RSSI and occurrencefrequency values by a respective multiplier value.

In one embodiment, if the difference does not exceed the first thresholdvalue, signal parameter information is again extracted and another tagscore is calculated for one or more of the RFID tags. The difference isdetermined between the highest another tag score and the next highestanother tag score and the difference is compared to the first thresholdvalue to determine a specific RFID tag using the tag scores. If thedifference between the tag scores again does not exceed the firstthreshold value, the various tag scores for each RFID tag are averagedto determine an average score for each RFID tag, and the differencebetween the highest average score and the second highest average scoreis determined and compared to a second threshold value. An RFID tagassociated with the highest average score is selected as the specificRFID tag based upon if the difference between the highest average scoreand the second highest average score exceeds the second threshold value.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate an embodiment of the inventionand, together with a general description of the invention given below,serve to explain the principles of the invention.

FIG. 1 is an illustration of a worker using an RFID reader fordetermining an RFID tag of a specified package according to oneembodiment of the present invention.

FIG. 1A is a schematic diagram of an RFID reader device in accordancewith one embodiment of the invention.

FIG. 1B is a schematic diagram of a computer device for use in oneembodiment of the invention.

FIG. 2 is a perspective view of a package as in FIG. 1, depicting anexemplary RFID tag and an identification label.

FIG. 3 is a flowchart illustrating the operation of one embodiment ofthe invention.

DETAILED DESCRIPTION

Referring to FIGS. 1-3, one embodiment of an RFID reader system 10 foridentifying a specific radio frequency identification (RFID) tag 12attached to an item 14 is illustrated. As shown in FIG. 1, a worker 16or other user managing the inventory of a business (e.g., fillingorders, restocking shelves, etc.), moves around an area where inventoryand associated RFID tags are located. While one exemplary embodiment, asdisclosed herein, might be useful for managing inventory, it will begenerally understood that the invention has applicability in anyenvironment where RFID tags are used. Therefore, the invention is not atall limited to just inventory uses.

In the illustrated example, worker 16 may pick up a specific item 14,such as a box, from a rack or shelf 18 holding a plurality of otherboxes 20 or other items. As the worker 16 moves the specific box 14 to acart or some other location, the worker 16 may record the identificationinformation of the specific box 14 for use by a central inventorymanagement system so as to record the disposition of the items 14, 20,or otherwise track movement of the items so that the inventory recordsremain accurate.

As illustrated in FIG. 1, worker 16 may carry a portable electronicdevice 22, such as a portable or mobile computer device, that isconfigured to process information and to communicate with a remote orcentral management system 23 (See FIG. 1A) and/or other workers. To thatend, device 22 might incorporate a Wi-Fi link to the remote or centralsystem 23. Once suitable such device 22 for use with the invention wouldbe a Talkman® device available from Vocollect, Inc. of Pittsburgh, Pa.The work environment, for example, might be a speech-directed orspeech-assisted work environment wherein the worker 16 would interfacewith a central system utilizing speech through speech recognition andtext-to-speech (TTS) functionalities. Device 22 might be coupled to aheadset 28, such as by a cord 29 or a suitable wireless link for thespeech interaction. Also coupled to device 22 is a portable RFID reader24 that is also coupled to device 22 through a cord 25 or a wirelesslink. RFID reader 24 may be carried or worn by the user as shown in FIG.1 and incorporates internal electronics and an internal or externalantenna, along with suitable controls for providing the desired RFIDreader functionality, according to aspects of the invention. FIG. 1illustrates just one possible embodiment of an RFID reader 24 that canimplement the invention.

FIGS. 1A and 1B illustrate components, including an RFID reader and acomputer device for implementing embodiments of the invention. Referringto FIG. 1A, an RFID reader 24 includes a housing 30 that containssuitable processing circuitry 32 controlled by a microprocessor or otherprocessor element 34 for implementing the RFID read functionality of thereader 24. In some embodiments of the invention, the processor andprocessing circuitry might also provide an RFID write functionality.However, the present invention is directed primarily to the readfunctionality of reader 24. The reader 24 also includes an antenna 36that is utilized to transmit and receive RF signals 38, with respect toan RFID tag 40. While antenna 36 is shown internal to the housing 30 ofRFID reader 24, the antenna might also be an external antenna. Theantenna 36 will generally be coupled to a suitable transceiver circuit31 that may be implemented as part of the processing circuitry 30 ofreader 24. The reader 24, and particularly the processing circuitry 32,may be coupled to computer device 22, such as by cord 25. Alternatively,processing circuitry 32 might also provide a wireless link, such as aWPAN link through a WPAN interface 27, for example, to communicate withcomputer device 22. Device 22 might then further process and utilize theRFID information obtained utilizing reader 24. In accordance with oneaspect of the present invention, the invention provides a selectivity tothe RFID read operation so that a desired RFID tag and the informationassociated therewith may be isolated from other RFID tags which are inthe vicinity of the desired tag and are also read during the RFIDreading process. In accordance with one aspect of the invention, signalparameter information is extracted or obtained regarding one or moreRFID tags. The signal parameters information is then used and furtherprocessed to determine a specific RFID tag.

In one embodiment, the signal parameter information is captured by theRFID reader and passed to computer device 22 for further processing. Inother embodiments, the processing to determine a specific RFID tag mightbe handled by the processing circuitry of RFID reader 24, or elsewhere,such as in computers or servers of remote system 23. Accordingly theinvention is not limited to the embodiments discussed and disclosedherein. Also, the processing and implementation of the algorithmdisclosed herein might be handled in part by processing circuitry ofvarious of the reader 24, device 22 and remote system 23 and thealgorithm does not have to be implemented completely in one component.

FIG. 1B is a block diagram of one exemplary embodiment of a computerdevice for use in implementing the invention. Specifically, device 22includes processing circuitry 50 which may include a processor element52 for controlling the operation of the computer device and otherassociated processing circuitry. Such processors generally operateaccording to an operating system, which is a software speech implementedseries of instructions. Processing circuitry 30 may also implement oneor more application programs in accordance with the invention. Processor52 may be a main processor chip coupled to a suitable companionprocessor circuit. Processing circuitry 50 may also be coupled toappropriate memory, such as flash memory 56 and random access memory 48.The processor and companion components 52, 54 may be coupled to thememory 56, 58, through appropriate buses such as an address bus 60 anddata bus 62. When the present invention is utilized within aspeech-based or voice-based system, the headset 23 may interface withdevice 22 through an appropriate audio coder/decoder chip or CODEC 70.To provide communications with remote system 23, such as over a wirelesslink, device 22 might also incorporate a suitable RF communication card66 coupled through an appropriate slot 64 with the processing circuitry50. As discussed herein, various of the processing provided by theinvention for the selection of a specific RFID tag from among aplurality of tags might be handled through the processing circuitry 50of device 22, through processing circuitry associated with the remotesystem 23, or directly through the processing circuitry of the RFIDreader 24, or a combination of various of those elements. In oneembodiment of the invention, the RFID reader is configured for sendingand receiving RF signals for detecting RFID tags and obtaining signalparameter information associated with the RFID tags. Computer device 22then runs the specific processing algorithm for using the signalparameter information regarding the RF signals received by the readerdevice from one or more of the RFID tags, and for using the signalparameter information to determine a specific RFID tag as discussedfurther herein below.

Referring again to FIGS. 1 and 2, an item or box 14 carries an RFID tag12 that contains an electronic product code (EPC) 36 that may be read byreader 24. The EPC or other identification information might also bewritten on a UPC bar code label 13, along with the UPC code information15. While the example illustrated herein for explaining the inventionrefers to a particular item or box 14 carrying an RFID tag, it would bereadily understood by a person of ordinary skill in the art that theRFID tags might also be utilized to provide information regarding alarger number of individual items, such as a case of items, a pallet ofitems, or some other manageable inventory unit that has multiple items,boxes, or packages therein. Furthermore, RFID tags might be utilized toprovide information regarding a particular location of an item, such asa warehouse aisle, shelf, slot, or bin within a larger warehouseenvironment. Accordingly, the present invention is not limited to theparticular type of information stored or use of an RFID tag.

The RFID reader 24 includes an antenna 36 that sends out, or transmits,electromagnetic energy in the form of RF radio waves or signals 38 to asurrounding area during the read process. The RFID tag 12 receives thiselectromagnetic energy and the circuitry of the tag is then energized tosend a reply RF or radio wave signal carrying or containing the EPCinformation or other information stored on the tag back to the RFIDreader 24. The reply or return tag RF signal 39 is received by theantenna 36 and directed to the processing circuitry 32 for furtherprocessing of the tag information. However, referring to FIG. 1, everyother box 20 on a storage rack 18 adjacent to the worker 16 also carriesan RFID tag 42 that receives the same electromagnetic energy 38 and maysend back a signal 39 with identification information to the RFID reader38. However, the other tags 42 may have information not associate withthe item 14 that is handled by the worker 16. Thus, the signal of thespecific RFID tag 12 on the desired box or item 14 and the informationassociated therewith must be reliably distinguished from the multiplesignals of the other RFID tags 42 on the non-selected items boxes 20 sothat the correct EPC 36 and product information can be recorded andprocessed by the reader 24, portable electronic device 22, andultimately by the central inventory management system or other system.

To implement the invention to determine the correct RFID tag 12, theRFID reader 24 includes circuitry, such as processing circuitry 32 thatis configured to extract or obtain signal parameter information asdiscussed below, and to operate, in one embodiment, in conjunction withdevice 22 to determine a specific RFID tag. For example, processingcircuitry 32 might incorporate or be implemented by an RFID module fromThingMagic of Cambridge, Mass. To extract, calculate or otherwise obtainsignal parameter information like RSSI values and “Times Read” values.

Specifically, the processing circuitry 32 is configured to extractinformation about RFID tags to be used by an algorithm for determiningthe proper or “best” tag that is read. A worker or user will pick up abox 14 with a tag 12, and they will initiate a scan with RFID reader 24.The algorithm is implemented in the invention within a certain timeperiod in order to determine the information from a box or other taggeditem in the worker's hand. If that information is determined promptlyand properly, that information can be utilized, such as to direct theworker on how to further process the item. For example, in oneembodiment of the invention, the inventive reader 24 might beimplemented with a TALKMAN® portable computer device 22, which utilizesspeech in a speech-directed or speech-assisted work environment.Information from the tag might be utilized by the TALKMAN® device 22,which then utilizes speech to direct a worker 16 how to further proceed.For example, the information that is read from the RFID tag might be anEPC code, a product description, or some other information. Thatinformation can be utilized by the worker to verify that the RFID readtask was correctly implemented. If the invention does not determineinformation from the RFID read process after a certain period of time,it will return feedback information to the worker that no tags werefound, such as in the form of an indication of “No Tags Founds”. If notags are found, the worker can either do a re-scan, or they can use someother mode of entering the information, such as an EPC code. Forexample, in utilizing a TALKMAN® device 22, the worker might use voiceto enter the EPC code or other information. Any re-scan process isrepeated as desired, and the algorithm of the invention will have aspecific period of time to correctly identify an item or otherwise readinformation from an RFID tag.

In accordance with one embodiment of the invention, the RFID readalgorithm of the invention has a certain period of time, for examplethree seconds, to figure out or determine the proper RFID tag from whichinformation is to be extracted or read. This time period might be brokendown into a series of individual scans. For example, three 750millisecond scans might be utilized. After the first scan, the inventiondetermines if it knows the desired tag or “best” tag. If so, the taginformation is returned as coming from the best tag or desired tag, andthat RFID information is then further processed. If not, another RFIDread or scan is done. After the second RFID scan, the invention againchecks to know if it has determined the “best” tag. If so, the desiredinformation read from the RFID tag is returned. If the best or desiredtag still is not known, an additional scan might be done. The processmight be repeated until the invention determines the best or desiredtag. If it still cannot determine the best tag after a particular timeperiod, the algorithm exits, and an indication such as “No Tags Found”might be returned to the worker or other user.

The RFID reader 24 performs a certain number of read cycles in apredetermined length of time, for example, the 750 milliseconds scan toobtain signal parameter information from one or more RFID tags. For eachRFID tag 12, 42 in the range or vicinity of the RFID reader 24, thereader evaluates the signal parameters associated with the signalsreceived from each of the tags. The RFID reader 24, and particularly theprocessing circuitry 32 or RFID module of the reader, detects andreturns a “received signal strength indication” (RSSI) parameter. TheRSSI parameter value for each tag is a measurement of the power presentin a received radio signal from the tag. The reader 24 also returns an“occurrence frequency” or “TIMES READ” parameter that has a valueindicative of the number of times the RFID tag 12, 42 has been read inthe 750 milliseconds scan. These received signal parameter values andparameter information are used by processing circuitry and a controlalgorithm described herein to determine the desired RFID tag. The RSSIvalues and TIMES READ values or occurrence frequency information arefurther processed to calculate a tag score for each RFID tag 12, 42detected according to the invention.

In one embodiment of the invention, processing circuitry in the computerdevice implements a control algorithm 100 to calculate the tag scoresand to determine which of the RFID tags 12, 42 detected by the RFIDreader 24 is the specific RFID tag 12 (best tag) on the specific box oritem 14 carried by the worker 16. The control algorithm 100 isschematically illustrated in the flow chart of FIG. 3 and will bedescribed in further detail below. The RFID reader 24 captures thesignal parameter information (e.g., RSSI and “TIMES READ” parameters)and sends the information to device 22 for further processing. Inanother embodiment, the RFID reader processing circuitry 22 mightperform the algorithm 100. In still another embodiment, the informationmight be forwarded to remote system 23 where the algorithm 100 isperformed. In still another embodiment, such further processing of theinformation collected by reader 24 and the performance of the algorithmmight be distributed over the various system components/devicesincluding the RFID reader, computer device 22 and remote system 23. Assuch, even though the exemplary system described herein uses the device22 for predominately processing algorithm 100, the invention is notlimited to just that scenario.

As discussed further hereinbelow, the present invention incorporates amultiple-step algorithm for determining the desired tag or best tagduring the reading process. If the best tag is not determined in thefirst stage, a second stage or even further additional stages might beutilized in accordance with aspects of the invention to determine thebest tag.

Generally speaking, the control algorithm 100 will have a totaldetection time period, such as 3 seconds for example, to determine theidentification information for the box 14 held by the worker 16. Theprocessing circuitry implementing the algorithm is pre-programmed tobreak up this total detection time period into smaller segments orscans, for example the 750 millisecond scans noted above. The detectiontime will be whatever might be appropriate for running individual scansand analyzing the results, and the invention is not limited to aparticular detection time or scan time. A worker 16 may begin a scan bypressing an appropriate button, or controlled element on the reader 24.The reader 24 might also be controlled via computer 22.

If a first individual scan of the RFID tags 12, 42 in the vicinity ofthe RFID reader 38 determines the specific RFID tag 12, then theprocessing stops the algorithm at that time and reports theidentification information to the worker 16 and/or the portableelectronic device 22 or remote system 23. If the processing circuitrycannot determine the specific RFID tag 12 from the first individualscan, more individual scans are conducted until either the specific RFIDtag 12 is determined or the detection time period finishes, or timesout. If the specific RFID tag 12 is not determined within the detectiontime period, then the processing circuitry of computer device 22 reportsthat no specific tag was detected. The worker 16 can then choose to runanother scan over another detection time period, or alternatively,manually or verbally enter the EPC 36 from the specific box 14 into theportable electronic device 22.

Referring to FIG. 3, the control algorithm 100 for the processingcircuitry 32 begins with an individual scan at step 101. As describedabove, the individual scan consists of sending out a signal in the formof a plurality of radio waves 38 from the antenna 40 of an RFID reader38 and receiving return radio wave signals 39 from all RFID tags 12, 42in the vicinity of the RFID reader output waves 38. Such scans result inreceived information from the received RF signals including signalparameter information. The processing circuitry, such as the processingcircuitry of computer device 22, analyzes the readings and receivedsignal parameters for the tags from the RFID reader 38 at step 102 todetermine the RSSI signal parameter value for each RFID tag 12, 42. Theprocessing circuitry also simultaneously analyzes the readings sent fromthe RFID reader 38 at step 103 to determine the occurrence frequency or“Times Read” signal parameter value for each RFID tag 12, 42.

Next, the RSSI values are normalized by the processing circuitry at step104 such as by dividing the RSSI for each RFID tag 12, 42 by the maximumRSSI value of all tags read during that particular scan. Similarly, theTimes Read values are normalized by the processing circuitry at step 105such as by dividing the Times Read for each RFID tag 12, 42 by themaximum Times Read value. Thus, a normalized value between zero and oneis calculated for the RSSI and Times Read values of each RFID tag 12, 42in accordance with one embodiment of the invention.

The processing circuitry and algorithm may need to emphasize one of thedetected metrics over the other. For example, it may be determined thatthe signal strength is more indicative of the specified RFID tag 12 thanthe occurrence frequency, or vice versa. Consequently, in oneembodiment, an RSSI multiplier and a Times Read multiplier are storedand used in the control algorithm 100. To favor the RSSI metric, theRSSI multiplier will be greater than the Times Read multiplier. In step106, the normalized RSSI values are multiplied by the RSSI multiplier todetermine an RSSI score for each RFID tag 12, 42. Similarly in step 107,the normalized Times Read values are multiplied by the Times Readmultiplier to determine a Times Read score for each RFID tag 12, 42. Tofavor the Time Read metric, that multiplier might be greater than theRSSI multiplier. Preferably, the RSSI multiplier and the Times Readmultiplier will add up to a total value of 2, such that the tag scoresremain normalized (between zero and one) when the RSSI score and theTimes Read score are averaged in step 108. However, this limitation onthe multipliers and tag scores is not absolutely necessary.

Averaging the RSSI score and the Times Read score is performed by addingthose two score values for each RFID tag 12, 42 and then dividing thesum by two. Therefore, the processing circuitry and algorithm 100determine a tag score for each RFID tag 12, 42 at step 108.

At this stage of the control algorithm 100, the processing circuitrydetermines which tag scores are the highest tag score and the nexthighest or second highest tag score if there are multiple tags andmultiple tag scores at issue. At step 109, the processing circuitry 32determines the difference between the highest and next highest tagscores and compares the difference between the highest tag score and thenext or second highest tag score to a stored first threshold valuestored used by the processing circuitry. If the difference between thetag scores is higher than the first threshold value, the controlalgorithm 100 continues to step 110. At step 110, the processingcircuitry determines if more than one RFID tag 12, 42 was detected. Ifmore than one tag was detected, then the RFID tag with the highest tagscore is selected and reported as the specific RFID tag 12. In step 111,reader 24 reports or causes device 22 to report that the specified RFIDtag 12 has been determined. In some embodiments, the portable electronicdevice 22 may report the EPC 36 or other identification informationassociated with the specified RFID tag 12. For example, an audibleindicator might be used to indicate that a specific RFID tag has beendetermined. An audible indication like voice from the headset 28 mightbe used so that a worker 16 can verify that the correct RFID tag 12 wasdetermined. If the processing circuitry and algorithm determine that thedifference between tag scores does not exceed the first threshold instep 109, or if it determines than only one RFID tag was detected instep 110, then the algorithm continues to step 112.

At step 112, the processing circuitry determines if the individual scanjust conducted in step 101 was the first scan. If so, the controlalgorithm returns back to step 101 to run another individual scan. Oncea second set or another set of tag scores is determined, the sameprocess of comparing the difference of the two highest tag scores to thefirst threshold is repeated at step 109. If this difference still doesnot exceed the first threshold value, then the processing circuitry willpass step 112 and continue to step 113. In step 113, an average tagscore for each RFID tag 12, 42 is determined by taking the simpleaverage of all tag scores for each RFID tag 12, 42 from the previousindividual scans. At step 114, the processing circuitry and algorithmcompares the highest average score and the second highest average scoreto determine if the difference between these average scores is greaterthan a stored second threshold value stored used by the processingcircuitry. If the difference between the average scores exceeds thesecond threshold, the control algorithm 100 continues to step 115. Atstep 115, the algorithm determines if the highest average score isgreater than a predetermined minimum average score threshold. If so,then the RFID tag with the highest tag score is the specified RFID tag12 at step 116, which reports the identification information, aspreviously described with respect to step 111. If the processingcircuitry determines that the difference between the average scores doesnot exceed the second threshold value in step 114, or if the processingcircuitry determines the highest average score was actually lower thanthe predetermined minimum average score threshold in step 115, thenalgorithm continues to step 117.

At step 117, the algorithm determines if there is enough time remainingin the detection time period for an additional individual scan. If so,the processing circuitry returns to step 101 of the control algorithmfor an additional individual scan and determination of whether thespecified RFID tag 12 has been located using tag scores or averagescores. If the processing circuitry determines that there is not enoughtime remaining for another individual scan at step 117, the processingcircuitry reports that no RFID tag was found at step 118. Again, theworker 16 can then determine whether another scan will be performed orwhether the EPC 36 or other identification information on the label 13of the specific box 14 will be entered manually or verbally.Consequently, the specific RFID tag 12 on the specific item 14 carriedby the worker 16 can be reliably determined and recorded using the RFIDreader 24 and the associated control algorithm 100, regardless of howmany other RFID tags 42 are in the vicinity of the worker 16.

A pair of example cases is provided below to further illustrate theoperation of the control algorithm 100. In each example, the followingparameters are set: the detection time period is 3 seconds; theindividual scan time is 750 milliseconds; the Times Read multiplier is1.2; the RSSI multiplier is 0.8; the first threshold value is 0.45; thesecond threshold value is 0.2; and the minimum average score thresholdvalue is 0.8. Note that these parameters are configurable to adapt thecontrol algorithm 100 for maximum effectiveness depending on the workconditions and RFID reader environment. For example, testing may be usedduring development to determine the best values. These values are thenset in software.

Example A

In the first case, the first individual scan at step 101 of the controlalgorithm 100 reports the following information: Tag A was detected withan RSSI value of 100 and a Times Read value of 20, while Tag B wasdetected with an RSSI value of 80 and a Times Read value of 5. At step104, the RSSI values are normalized by dividing each RSSI value by themaximum RSSI value, which is 100 in this example. Therefore, thenormalized RSSI values are 1.0 and 0.8. At step 105, the Times Readvalues are also normalized by dividing each Times Read value by themaximum Times Read value, which is 20 in this case. Therefore, thenormalized Times Read values are 1.0 and 0.25. These steps provide Tag Awith a normalized RSSI of 1.0 and a normalized Times Read of 1.0, andTag B with a normalized RSSI of 0.8 and a normalized Times Read of 0.25.At steps 106 and 107, the normalized values are further emphasized bymultiplying them by the respective RSSI multiplier and Times Readmultiplier. This provides Tag A with an RSSI score of 0.8 and a TimesRead score of 1.2, while Tag B has an RSSI score of 0.64 and a TimesRead score of 0.3. At step 108, these scores (i.e. RSSI and Times Read)are averaged by adding them together and dividing by two. This yields atag score for Tag A of 1.0 while the tag score for Tag B is 0.47. Atstep 109, the processing circuitry 32 determines that the differencebetween these two highest tag scores is 0.53. The 0.53 value exceeds thefirst threshold of 0.45 (Step 109). Because more than one tag wasdetected (Step 110), Tag A will be reported as the specific RFID tag atstep 111 and the control algorithm 100 ends.

Example B

In the second case, the first individual scan at step 101 of the controlalgorithm 100 reports the following information: Tag A was detected withan RSSI value of 100 and a Times Read value of 20, while the nexthighest tag, Tag B, was detected with an RSSI value of 80 and a TimesRead value of 10. At step 104, the RSSI values are normalized bydividing each RSSI value by the maximum RSSI value, which is 100 in thiscase. At step 105, the Times Read values are normalized by dividing eachTimes Read value by the maximum Times Read value, which is 20 in thiscase. These steps provide Tag A with a normalized RSSI of 1.0 and anormalized Times Read of 1.0, and Tag B with a normalized RSSI of 0.8and a normalized Times Read of 0.5. At steps 106 and 107, the normalizedvalues are emphasized by multiplying them by the respective RSSImultiplier and Times Read multiplier. This provides Tag A with an RSSIscore of 0.8 and a Times Read score of 1.2, while Tag B has an RSSIscore of 0.64 and a Times Read score of 0.6. At step 108, these scoresare averaged to determine that the tag score for Tag A is 1.0 while thetag score for Tag B is 0.62. At step 109, the processing circuitry 32determines that the difference between these two highest tag scores is0.38, which does not exceed the first threshold of 0.45. Thus, theprocessing circuitry 32 returns through step 112 back to step 101 toconduct another individual scan.

In the second individual scan, the following information is provided:Tag A was detected with an RSSI value of 100 and a Times Read value of20, while Tag B was detected with an RSSI value of 90 and a Times Readvalue of 12. At step 104, the RSSI values are normalized by dividingeach RSSI value by the maximum RSSI value, which is 100 in this case. Atstep 105, the Times Read values are normalized by dividing each TimesRead value by the maximum Times Read value, which is 20 in this case.These steps provide Tag A with a normalized RSSI of 1.0 and a normalizedTimes Read of 1.0, and Tag B with a normalized RSSI of 0.9 and anormalized Times Read of 0.6. At steps 106 and 107, the normalizedvalues are emphasized by multiplying them by the respective RSSImultiplier and Times Read multiplier. This provides Tag A with an RSSIscore of 0.8 and a Times Read score of 1.2, while Tag B has an RSSIscore of 0.72 and a Times Read score of 0.72. At step 108, these scoresare averaged to determine that the tag score for Tag A is 1.0 while thetag score for Tag B is 0.72. At step 109, the processing circuitry 32determines that the difference between these two highest tag scores is0.28. This difference again does not exceed the first threshold value of0.45. Now that two scans have been performed, the processing circuitry32 moves to step 113 in the control algorithm 100.

At step 113, the average score for each tag is calculated as follows:Tag A had a first tag score of 1.0 and a second tag score of 1.0, theaverage of which is also 1.0. Tag B has a first tag score of 0.62 and asecond tag score of 0.72, the average of which is 0.67. At step 114, thehighest average score of Tag A (1.0) is compared to the second highestaverage score of Tag B (0.67). The difference between these averagescores is 0.33, which exceeds the second threshold value of 0.2. Assuch, the processing circuitry 32 continues to step 115, where theprocessing circuitry 32 determines that the highest average score (1.0)does exceed the predetermined minimum average score threshold of 0.8.Thus, Tag A will be reported as the specific RFID tag at step 116 andthe control algorithm 100 ends. If the average score determinations atstep 114 and step 115 had been unsuccessful, another individual scanwould have been run in this example because of remaining time.

If subsequent scans yield no tags, the reader 24 reports that no tag isfound (Step 118). Therefore, the present invention provides a way ofinsuring that the desired RFID tag is read, and that the desiredinformation is extracted from that tag for further use and processing ofthe tag information and the item associated with that tag information.The various alternative scenarios set forth above and other scenarioshelp a worker or user make a proper RFID scan and read, and createsgreater efficiency in the RFID reader process. Furthermore, theinvention removes the guesswork associated with trying to obtain theproper RFID read, and also does not require that the RFID reader bespecifically focused in the direction of one particular item. Theinvention filters any stray information from other RFID tags, andinsures that the proper information is utilized and processed.

While the present invention has been illustrated by the description ofthe embodiment thereof, and while the embodiment has been described inconsiderable detail, it is not the intention of the applicant torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. For example, the average score calculationsand determinations may not be performed until after a third individualscan in an alternative embodiment. Therefore, the invention in itsbroader aspects is not limited to the specific details representativeapparatus and method, and illustrative examples shown and described.Accordingly, departures may be made from such details without departurefrom the spirit or scope of applicant's general inventive concept.

What is claimed is:
 1. A system for identifying a specific RFID tag, thesystem comprising: RFID reader circuitry that sends and receives RFsignals to detect RFID tags and for obtaining signal parameterinformation associated with the RFID tags including a plurality ofdifferent signal parameter values associated with the RFID tags;processing circuitry that uses the signal parameter information for oneor more tags of the RFID tags to calculate a tag score for the one ormore RFID tags and gives a different weight to at least one of thesignal parameter values over another signal parameter value in thecalculation of the tag score by multiplying the at least one signalparameter value by a respective multiplier.
 2. The system of claim 1wherein the RFID reader circuitry and the processing circuitry arecontained in a single device.
 3. The system of claim 1 wherein the RFIDreader circuitry and the processing circuitry are contained in separatedevices.
 4. The system of claim 1 further comprising an RFID readercontaining the RFID reader circuitry and a computer device containingthe processing circuitry.
 5. The system of claim 1, wherein the RFIDreader circuitry obtains signal parameter values including a receivedsignal strength indication (RSSI) value and an occurrence frequencyvalue for the one or more RFID tags and the processor circuitry isoperable for using RSSI values and occurrence frequency values tocalculate tag scores for one or more tags of the RFID tags.
 6. Thesystem of claim 5 wherein the processing circuitry averages the RSSI andoccurrence frequency values for each of the one or more RFID tags tocalculate a tag score for each of the one or more RFID tags.
 7. Thesystem of claim 5 wherein the processing circuitry normalizes the RSSIvalues and occurrence frequency values by dividing the RSSI value by amaximum detected RSSI value, and normalizing the occurrence frequencyvalue by dividing the occurrence frequency value by the maximum detectedoccurrence frequency value.
 8. The system of claim 1 wherein theprocessing circuitry determines a difference between a highest tag scoreand a next highest tag score for the one or more RFID tags and comparesthe difference to a first threshold value to identify the specific RFIDtag using the tag scores.
 9. The system of claim 8 wherein theprocessing circuitry selects the RFID tag associated with the highesttag score as the specific RFID tag if the difference exceeds the firstthreshold value.
 10. The system of claim 8 wherein when the differencedoes not exceed the first threshold value, to again obtain signalparameter information associated with the RFID tags and to calculateanother tag score for the one or more RFID tags and to determine adifference between a highest another tag score and a next highestanother tag score and to compare the difference between a highestanother tag score and a next highest another to score to the firstthreshold value to identify the specific RFID tag using the another tagscores.
 11. The system of claim 10, wherein when the difference betweenthe another tag scores again does not exceed the first threshold value,the processing circuitry: averages the tag score and the another tagscore for each RFID tag to determine an average score for each RFID tag;determines a difference between the highest average score and the secondhighest average score; compares the difference between the highestaverage score and the second highest average score to a second thresholdvalue; and selects the RFID tag associated with the highest averagescore as the specific RFID tag based upon if the difference between thehighest average score and the second highest average score exceeds thesecond threshold value.
 12. The system of claim 11 wherein theprocessing circuitry is further operable, if the difference between thehighest average score and the second highest average score exceeds thesecond threshold value, to determine if the highest average score isgreater than a minimum average score threshold.
 13. The system of claim5 wherein the at least one RSSI value and occurrence frequency value isnormalized before emphasizing the value with a respective multipliervalue.
 14. The system of claim 1, wherein the processing circuitryprovides an audible indication when the specific RFID tag has beendetermined.
 15. A method for identifying a specific RFID tag, the methodcomprising: sending and receiving RF signals to detect RFID tags andobtain signal parameter information associated with the RFID tags, thesignal parameter information including a plurality of different signalparameter values associated with the RFID tags; using the signalparameter information for one or more RFID tags and calculating a tagscore for the one or more RFID tags; and in calculating the tag score,weighting at least one signal parameter values over another signalparameter value by multiplying the at least one signal parameter valueby a respective multiplier value.
 16. The method of claim 15 furthercomprising determining a received signal strength indication (RSSI)value and an occurrence frequency value for each of the for the one ormore RFID tags and using RSSI values and occurrence frequency values tocalculate tag scores for one or more of the RFID tags.
 17. The method ofclaim 16 further comprising averaging the RSSI and occurrence frequencyvalues for each of the one or more RFID tags to calculate a tag scorefor each of the one or more RFID tags.
 18. The method of claim 17further comprising determining a difference between a highest tag scorefor the one or more RFID tags and a next highest tag score and comparingthe difference to a first threshold value to identify the specific RFIDtag using the tag scores.
 19. The method of claim 18 further comprisingselecting the RFID tag associated with the highest tag score as thespecific RFID tag if the difference exceeds the first threshold value.20. The method of claim 15 further comprising normalizing the RSSI valueand occurrence frequency value by dividing the RSSI value by the maximumdetected RSSI value, and by dividing the occurrence frequency value bythe maximum detected occurrence frequency value.